Quiet movies

[rhobite]

Hi,

I seem to be creating very quiet movies in Gordian Knot. In order to hear them I have to turn my volume way up, which causes my speakers to hiss. If I play the MP3 audio from the movie in Winamp, I can tell by looking at the spectrum analyzer that the audio is almost silent.

What's the best way to normalize the audio in my movies? Here's my Besweet command line, just to see what I'm using now:

C:\PROGRA~1\GORDIA~1\besweet.exe -core( -input "C:\movies\Unfinished\Crouching Tiger, Hidden Dragon\crouching AC3 T01 3_2ch 384Kbps DELAY 0ms.ac3" -output "C:\movies\Unfinished\Crouching Tiger, Hidden Dragon\crouching AC3 T01 3_2ch 384Kbps DELAY 0ms.mp3" -logfile "C:\movies\Unfinished\Crouching Tiger, Hidden Dragon\crouching AC3 T01 3_2ch 384Kbps DELAY 0ms.log" ) -ota( -G max ) -azid( -L -3db -c normal ) -lame( --alt-preset cbr 128 --scale 1 ) -profile( Gordian Knot 0.26 )

I was thinking of using the -g option for azid, but Gknot specifically warns against this. Why is that? We're already doing the dynamic range compression, but if the movie is very quiet that doesn't make it any louder. Why not add some sort of normalization?

[snowbeach]

Hi rhobite!

Your question regarding -g option in GKnot is very good! I asked it too today! Oooops! Have a look at Audio Transcoding Parameters in GKnot (http://forum.doom9.org/showthread.php?threadid=37280) :rolleyes: I really do not know, why you should not use it, because it works!

The best way to normalize, I experienced, is...

BeSweet.exe -core( -input "Movie AC3 T01 3_2ch 384Kbps DELAY 0ms.ac3" -output "Movie AC3 T01 3_2ch 384Kbps DELAY 0ms.mp3" -logfile "Movie AC3 T01 3_2ch 384Kbps DELAY 0ms.log" ) -azid( -c normal -g max -L -3db ) -ota( -d 0 ) -lame( -p --alt-preset 128 )

Got always nice results, check it out...
Normalize with -g max in Azid.
Ota command stands for the delay values of your AC3 file. (e.g. -103ms -> -ota( -d -103) )
I always use -p option to turn on CRC error protection. "It will add a cyclic redundancy check (CRC) code in each frame, allowing to detect transmission errors that could occur on the MP3 stream. However, it takes 16 bits per frame that would otherwise be used for encoding, and then will slightly reduce the sound quality."

Greets. ;)

[N_F]

The key to raise the volume in your movies isn't really normalizing, if you select DspGurus preconfigured profile for abr 128 it'll look something like this:

"d:\Movie Tools\BeSweetv1.3 GUI 0.6b58\BeSweet.exe" -core( -input "d:\Temp\married_with_children_-_s02e13_-_you_better_watch_out.mp2" -output "d:\Temp\married_with_children_-_s02e13_-_you_better_watch_out.mp3" -logfile "D:\Movie Tools\BeSweetv1.3 GUI 0.6b58\BeSweet.log" ) -azid( -n1 -c normal -g 10db -L -3db ) -ota( -G max ) -lame( --scale 1 -p --alt-preset 128 )

The key here is -g 10db which will raise your overall volume by 10 db (please correct me if I'm wrong).

[snowbeach]

Now, it seems very clear to me, after I looked at my GKnot log. I added the -g option in GKnot and got the following command line result.

Commandline: D:\GORDIA~1\besweet.exe -core( -input "E:\Movies\temp\MATRIX AC3 T01 3_2ch 384Kbps DELAY -103ms.ac3" -output "E:\Movies\temp\MATRIX AC3 T01 3_2ch 384Kbps DELAY -103ms.mp3" -logfile "E:\Movies\temp\MATRIX AC3 T01 3_2ch 384Kbps DELAY -103ms.log" ) -ota( -G max ) -azid( -L -3db -c normal -g max ) -lame( -p --alt-preset 128 --scale 1 ) -profile( Gordian Knot 0.26 )

GKnot is using the PostGAIN (-ota( -G max)) method! That is why it makes no sense to insert PreGAIN (-azid(-g max)) method of Azid! What is better? Pre- or PostGAIN? An excerpt out of BeSweets ota.txt (you can find it in the Help directory of BeSweet)!
Important :
------------
"-G" switch differs from "-g" in the fact that "-G" will assert gain on a MP3/OGG after encoding prcoess was finished, while "-g" will assert the gain before encoding.
that's why "-g max" will take almost 50% time longer than "-G max".
about the quality difference between the two methods, here's a quote of 'tangent' :
[quote]I believe that the benefits of postgain and more than worthwhile. Quality wise, it would not be the same as pregain, and one cannot absolutely say if it would be worse, better or similar. I can say that for most people out there the difference is inaudible, and in my opinion the quality should be better. This, plus the fact that postgain method is faster is enough for me to choose the postgain method.

One last final advantage of post-gain is that you can guarantee that with post-gain applied, you can absolutely guarantee that the decoded playback will not clip and will have the highest volume possible (within 1.5dB). With pre-gain, there is no such guarantee, and you cannot be sure if the decode playback will clip or have the highest volume possible."
[end of quote]
I do not agree with this opinion, because I experienced better results with the -g option of Azid. That is why I suggest to use BeSweet for audio encoding! The options can be then something like this ... -azid( -c normal -g max -L -3db ) -ota( -d 0 ) -lame( -p --alt-preset 128 )

[rhobite]

Snowbeach: Thanks for the info, I guess I'll try a couple movies with pre and post-gain. BTW, putting CRC in your MP3 is almost useless, as I've read that most players ignore this information. Usually all that CRC does is reduce your MP3 quality a little bit.

N_F: I'll try that too, but I was worried that amplifying by a set decibal number would introduce clipping into the loud parts of the movie. Although it probably won't have that effect on Crouching Tiger, which seems to be a VERY quiet movie.

[N_F]

Originally posted by rhobite
N_F: I'll try that too, but I was worried that amplifying by a set decibal number would introduce clipping into the loud parts of the movie. Although it probably won't have that effect on Crouching Tiger, which seems to be a VERY quiet movie.

I don't know, I just use the settings DspGuru recommends and trust him blindly :) Anyway, I'm fully satisfied with the results from it.